1. Field of the Invention
This invention relates to an anti-theft apparatus, an anti-theft method and an anti-theft program which can surely detect a theft state of a vehicle, such as inclination and vibration of a vehicle due to a theft action, even in a case that various acceleration sensors, which are mounted on a vehicle for an application other than anti-theft, are also used for anti-theft.
Also, it relates to an expansion permission apparatus of an air bag, an expansion permission method and an expansion permission program for giving expansion permission on the occasion of expanding an air bag to an air bag apparatus for expanding an air bag on the basis of a detection result of an acceleration sensor, and in particular, relates to an expansion permission apparatus of an air bag, an expansion permission method and an expansion permission program in which, without making a structure of an air bag apparatus complicated by use of an anti-theft apparatus, it becomes possible to configure an electronic safing system at less cost, and which can secure reliability of an air bag operation.
2. Description of the Related Art
In the past, in a vehicle such as an automobile, an auto-bicycle and so on, in order to prevent theft of a parked vehicle and a tire by use of jack-up and so on, there was such a case of mounting anti-theft dedicated ECU (electronic control unit) in which an inclination sensor was incorporated. Further, in recent years, for the purpose of reducing a cost, there has been such a proposal that the anti-theft dedicated ECU is not mounted, but an acceleration sensor inherently mounted on a vehicle for an application other than anti-theft is also used for an application of anti-theft.
For example, in JP-A-2002-67882, disclosed is an anti-theft apparatus in which an inclination sensor (acceleration sensor) for use in detecting reversal which is incorporated in a reversal detection ECU (electronic control unit for detecting reversal of a vehicle to stop fuel injection and ignition) which was mounted on an auto-bicycle is also used for anti-theft. Concretely speaking, it is an anti-theft apparatus in which, by detecting a vibration component of a vehicle by use of the inclination sensor, the inclination sensor is also used as a vibration sensor for use in anti-theft.
However, in case that various acceleration sensors, which are mounted on a vehicle for an application other than anti-theft, are intended to be used also for anti-theft as an inclination sensor from the same view point as above, there was such a problem that it is not necessarily possible to surely detect inclination of a vehicle from a problem of detection sensitivity.
Explaining this concretely, for example, in an air bag ECU (electronic control unit for detecting a mechanical shock from a predetermined direction to have an air bag ignited) which is mounted on a vehicle, an acceleration sensor for detecting the shock is incorporated, but this detection sensitivity is generally set up to approximately ±50 G–±300 G from a view point of shock detection. In other words, to cite an example, detection sensitivity of a Y direction acceleration sensor (see, FIG. 2A) which was disposed in a front collision air bag ECU is approximately ±100 G.
On one hand, in case that a vehicle was inclined due to jack-up and so on, as shown in FIG. 2B, change of acceleration due to gravity which does not normally appear as an output and is applied in a vertical direction appears in an acceleration sensor. And, by utilizing this output change of the acceleration sensor, a relation of “inclination angle—lift amount—acceleration sensor output” as shown in FIG. 2C is logically derived. In addition, the relation shown in FIG. 2C is one on the assumption that a vehicle with vehicle width of 165 cm was inclined due to jack-up and so on.
Here, focusing on a relation which was shown in FIG. 2A, incase that such a state that a vehicle was lifted in a Y direction by approximately 20 cm was assumed to be a critical point for anti-theft, in this state, an output of an acceleration sensor becomes approximately 125 mV, and therefore, in order to surely detect this inclined state from the output of the acceleration sensor, detection sensitivity of approximately ±2 G is required. Therefore, in the acceleration sensor which was cited above as an example, there is necessarily a limit to detect the critical point for anti-theft.
In this manner, even if various acceleration sensors, which are mounted on a vehicle for an application other than anti-theft, are also used for anti-theft as an inclination sensor, detection sensitivity is too much low as it is, and therefore, it is not necessarily possible to surely detect inclination of a vehicle due to jack-up and so on, and it was difficult to surely prevent theft of a vehicle and a tire.
In addition, in the same manner as this, in case that the acceleration sensor is intended to be used for anti-theft as a vibration sensor (i.e., vibration of a vehicle due to a turbulent action which may lead to theft is intended to be detected), vibration generated due to such action is small as compared with vibration at the time of vehicle collision (i.e., detection sensitivity without any modification is too much low), and therefore, it is not necessarily possible to surely detect vibration of a vehicle, and it was difficult to surely prevent theft of a vehicle and a tire.